Urban planning with respect to flood risk

Transcription

1 Urban planning with respect to flood risk Dalia Todary-Michael Rotteneder Leonhard 1 1

2 Outline Urban Planning Principles for Flood Risk Development and Land Use Policy Case Studies: Carawang Seoul Wien-fluss 2 2

3 Urban Planning Approaches The heart of master planning lies in: Identifying the problem Opportunities and constraints Goals and objectives Establishment of policy Establishment of standards to measure future development and govern current statuses of protective measures. 3

4 Urban Planning Approaches Objectives of Flood Management: - reducing exposure of people and property to flood hazards - reducing existing level of flood damages - minimizing soil erosion and sedimentation problems - protecting environmental quality and well-being by reducing in-thecatchment pollution - improving the usefulness of floodplains - minimizing receiving water pollution 4

5 Urban Planning Approaches Flood management objectives should be implemented into policy. Urban Master Planning process involves: Policy, goals, criteria. Urban Flood and Pollution Control (UFPC) Master Plan. To be effective, the policy must recognize the need to treat developed and undeveloped land separately. This document is becoming an inevitable planning document that directs flood and pollution controlled urbanisation in an undeveloped or underdeveloped area or mitigates adverse consequences of flooding and pollution in the areas that have already experienced flood and pollution problems. 5

6 Urban Planning Approaches Two forms of storm-water master planning: Preventive: Preventive would follow a sequence of evaluation of a single stormwater basin. Remedial: Remedial would follow a framework less standardised and more site-specific. Following the UFPC Master Plan approval, when funding is assured, detailed plans and designs are prepared as an advanced step toward implementation. Preventive master plan for an individual basin includes evaluation of the basin hydrology under existing conditions in order to identify existing drainage problems. Two approaches are common: to perform cost-benefit analysis where flood damages can be identified, the minimum of which determines the solution to implement, or to comply with the locally adopted storm water drainage criteria based on a pre-determined, commonly accepted, level of risk. 6

7 Development and Land Use Policies Regulation of floodplain Biodiversity, good groundwater supply, good water quality, natural flood and erosion control. 7

8 Development and Land Use Policies Urban runoff does not always flow perpendicularly to the contour lines of the natural terrain because of many objects and infrastructure facilities that constitute an urban environment. Urbanisation of a natural floodplain increases the susceptibility of the neighbouring land to floods, generally making it more difficult for drainage planners to plan around. 8

9 Development and Land Use Policies Land use and zoning plans: Three foundation floodplain developments: preventing development from constricting floodway and allowing the flood fringes to be preserved for agricultural or recreational purpose preventing development from constricting floodway and allowing the flood fringes to obtain housing, commercial or industrial purpose as long as results are only insignificant increase in the surface elevation restricting the use of the flood plain and leaving it in its original unoccupied state Land use management employs two principal options: zoning control and development/building control. Zoning control includes designating, by the responsible authority, the type of activity that can be undertaken within the flood-prone area. Most of the physical, social and economic problems associated with flooding, soil erosion and water pollution stormwater are attributable to inappropriate urbanisation of the floodplain, unwise land use within the city, insufficient attention to drainage in urban planning, ineffective updating of existing stormwater control facilities and lack of enforcement of zoning ordinances. Those types of floodplain development actions are institutionally accompanied by: - legal measures that enforce zoning, density and pace of development - taxation measures that may guide development away from hazard areas - government action that may alter existing land use or require compulsory purchase of the flood-prone land 9

10 Development and Land Use Policies Land use planning is the tool for creating another significant step, a land use program (type of activities, development pace, population restrictions etc.) This is usually supported by: infrastructure relocation, permanent evacuation, open space programs, zoning ordinances for limiting types of land use, and others: - regional planning - subdivision regulation - building codes of practice - housing codes of practice - sanitary and other utility codes of practice - redevelopment policies such as proper design of utilities - source pollution control - public acquisition - flood proofing 10

11 Development and Land Use Policies Further points: Artificial structures should be built in harmony with the rest of the environment. 11

12 This is another example of embankment reinforcements to prevent damage to floodplain developments by means of 12

13 Case studies: Carawang Location: Indonesia Western Java Carawang City Catchment Area: 7180 km 2 8 Cities 13 13

14 Case studies: Carawang Problems: High level of urbanization in the river basin conversion of forest areas Solution: Strtict restrictions for the expansion of urban areas This policy in the short term will impact negatively on the provision of affordable housing but in the long term this policy will be more sustainable

15 Case studies: Seoul River: Cheonggyecheon Removal of a 6 Lane Highway Building of 22 Bridges Recreation of a nearly 6 km river Flood control tunnels in the embankmant walls 15 15

16 Case studies: Seoul 16 16

17 Future of Wien-fluss? Bring the Traffic to Tunnels A close to natural surface river A big flood channel Maybe dual use from the flood channel as traffic space

18 End Thank you for your attention 18 18